Optical arrangement for producing two anamorphotically compressed images correlated by an interocular base distance

ABSTRACT

An optical arrangement for producing two anamorphotic images correlated by a interocular base distance, includes two basic optical systems and two afocal anamorphotic systems. The basic optical systems are parallel and spaced laterally by an interocular base distance. Each anamorphotic system has a cylindrical negative lens system mounted adjacent the object space side of the respective basic optical system and a cylindrical positive lens system mounted adjacent the image space side of the respective basic optical system.

FIELD OF THE INVENTION

The present invention relates to optical imaging and to an arrangementof optical elements for producing pairwise, interocular-correlated,anamorphotically linearly compressed images. The arrangement isparticularly useful for the exposure of film material suitable for thehorizontally expanded reproduction of images retained on film in thisway, particularly on a double-curved projection plane as truestereophotographic images.

BACKGROUND OF THE INVENTION

When showing films, attempts have frequently been made to give theviewer the impression that he was part of the photographicallyrepresented events. Numerous technical solutions have been proposed inview of the attractiveness of a close to reality representation of agenerally optically dramatic sequence, such as objects flying towardsthe viewer, precipitous journeys, etc. These sequences lead to manydifferent reactions on the part of the viewer.

U.S. Pat. No. 4,129,365 describes a wide-angle projection arrangement(Cinerama) in which three projectors project on to a cylindricallycurved projection surface a picture formed from three images giving theviewer a panoramic effect. Through the use of a special type of flexiblemirror, projection can take place without the viewers seeing theprojectors, which projectors are disturbingly positioned below andsomewhat in front of the viewers. The necessary transverse magnificationof the partial images is produced with anamophotically acting opticalmeans. However, the apparatus cost is considerable for three cameras andtwo reflecting mirrors for each camera. Special measures are alsorequired to produce an uninterrupted transition between the partialimages.

The apparatus expenditure is considerably reduced by the projectionarrangement described in U.S. Pat. No. 4,154,514 to Harvey. An image isproduced on a projection plane deeply curved in arc-like manner on oneside giving the viewer the impression of spatial or three-dimensionalaction. Projection takes place over an angle between 138° and 153° ontoa cylindrically curved plane. Compared with conventional 3D-systems,using an angle of normally less than 90°, no additional optical viewingaid is required for producing the three-dimensional impression.

The projection arrangement described in the Harvey patent merelycomprises a single projector with anamophotic aids positioned in frontof it to produce the necessary very large width/height ratio. Standard35 mm films with anamorphic images are used for projection purposes.

The optical three-dimensional effect is largely based on the deepcurvature of the projection plane, which plane surrounds the viewer ofthe photographic scene or occupies the viewer's field of the vision suchthat the picture frame is no longer perceived. Thus, a picture, asperceived by the two eyes with the given interocular distance, isprocessed by the brain to give a three-dimensional impression.

Another technical solution involves two anamorphotically compressedimages correlated with respect to one another with an interoculardistance and represented on a standard 70 mm film in a ratio of 1:2.During projection, there is a stereo wide-screen picture effect with twopictures correlated in the interocular distance and defined by differentpolarization. A viewing aid is provided in the form of a viewer with twopolarizers inclined towards one another.

For recording the images two basic optic systems are connected in frontof anamorphic attachments, and their optical axes are essentially spacedthe average spacing of a pair of human eyes. Since the centre-to-centrespacing of the image on the film is determined by the image format andis generally much smaller than the spacing of the optical axes, therepresented object distances are adapted in known manner by reflectingmirrors.

As a function of the conventional anamorphic attachment/basic opticscombination, relatively large overall lengths are required, so that thecamera angle is limited. The convergence control of the two correlatedimages is also more difficult for extreme wide-angle projection. Theincident light beams of the two optics must be transversely displacedwith respect to the optical axes and at the same time focused as soon asthe taking distance changes.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an optical arrangementfor taking wide-angle stereo pictures using simultaneous anamorphoticcompression having a particularly simple optical arrangement, a smalloverall length and few movable parts.

Another object of the present invention is to provide an opticalarrangement having a compact, anamorphotic stereo image block tosimultaneously perform convergence control and focusing by the sameoptical element.

The foregoing objects are obtained by an optical arrangement forproducing two anamorphotic images correlated by a interocular basedistance, comprising two basic optical systems and two afocalanamorphotic systems. The basic optical systems are spaced laterally byan interocular base distance. Each anamorphotic system has a cylindricalnegative lens system mounted adjacent the object space side of therespective basic optical system and a cylindrical positive lens systemmounted adjacent the image space side of the respective basic opticalsystem.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses preferredembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a diagramatic side elevational view of an optical arrangementaccording to the prior art;

FIG. 2 is a diagramatic side elevational view of an optical arrangementaccording to a first embodiment of the present invention; and

FIG. 3 is a diagramatic side elevational view of an optical arrangementaccording to a second embodiment of the present invention, providing acomplete anamorphotic stereo image block.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 essentially shows an optical arrangement with a basic opticalsystem or basic optics 10 and a cylindrical anamorphotic attachmentarranged on the object space side of basic optical system 10. Thisupstream-mounted anamorphotic attachment comprises a plurality ofelements including cylindrically ground lenses spaced by a distance a. Anegative cylindrical front lens 16 or a cylindrically ground dispersionlens, and a positive cylindrical lens 17 or a cylindrically groundcollective lens are provided. Along the optical path, basic opticalsystem 10 follows and normally corresponds to conventional cameraoptics. By correspondingly dimensioning the anamorphotic attachment, theattachment is optically adapted to the camera optics. The total lengthfrom front lens 16 to the plane of film 2 is a+b, and can varyconsiderably as a function of the optical design.

On the film plane this arrangement forms, in the horizontal imagedirection, an image of the taken object compressed, e.g., by a factor of2 or double.

Two such arrangements must be used for stereoscopic recording with theiroptical center or principal axes parallel and at a distance ofapproximately 70 mm. The distance is the average interocular distance orbase distance.

Unless preference is given to the taking of the stereo images with twoseparate cameras, the interocular base distance must be linearlytransformed to a distance defined by the film format used as one of themany boundary conditions. For extreme wide-angle photographs with asensible light intensity, a base distance of approximately 70 mm for theoptical axes of two lenses is closer to the lower limit. Thus, theselection of the anamorphotic attachments causes serious dimensioningproblems.

In addition, the wide-angle characteristics of the basic optics areimpaired by the overall length of the anamorphotic attachment. Thenecessary distance in front of the attachment is such that the desirewide-angle projection cannot be realized on the photographic recordingside.

FIG. 2 shows an arrangement of optical elements where, according to thepresent invention, a more compact construction with a better or morecomplete utilization of the wide-angle characteristics of the basicoptical system is provided. The multi-element cylindrical anamorphoticattachment 25 is functionally separated with basic optical system orbasic optics 10 arranged within the scope of distance a'. The novelanamorphotic block comprises a negative cylindrical lens 26, i.e., acylindrically ground dispersion lens, arranged on the object space sideof basic optical system 10, followed by the basic optics which can belocated very close to the dispersion lens 26 as a result of thismeasure. Following along the optical path, a positive cylindrical lens27, i.e., a cylindrically ground collective lens, is located in front ofthe film plane 2 on the image space side of the basic optical system.

This functional nesting of the basic optical system and the anamorphoticsystem provides a much shorter overall length, because the space betweenthe two cylindrical lenses is virtually completely used. The angle α,for suitably selected basic optics, is at least 100°, providing markedimprovement of the wide-angle characteristics due to the novelanamorphotic attachment 25. The nesting in a' and the telescoping of theoverall lengths provide a total length b' smaller than (a+b). In thisarrangement, the object imaging on the film plane is focused by thedisplacement of the complete optical part 25.

The short overall length obtained permits significantly smaller frontlens diameters or a constant light intensity. Two parallel opticalsystems, as illustrated in FIG. 2, are used to form an anamorphoticblock suitable for stereo photography. Such an optical arrangement isillustrated in FIG. 3.

For each basic optics 10 and 10', negative cylindrically ground lenselements 36 and 36a or 36' and 36'a are provided on the object spaceside. A spherical negative achromat serves as the front lens 38 or 38'for further shortening the focal length. This leads to a furtherincrease of the taking angle α, which consequently considerably exceeds100°.

The optical and geometrical dimensioning of the front lenses 38 and 38'can be selected such that, for a predetermined spacing of the centralaxes at the interocular distance or I.O.D., the peripheral portions ofthe lenses are brought towards one another to such an extent that theoptical separating element 40 between the two systems has a thicknessof, e.g., 1 mm.

On the image space side, each basic optics 10 or 10' is followed by apositive cylindrically ground lens element 37 or 37'.

In the optical elements covered by arrangement 35, the desiredanamorphotic compression, e.g., of 1:2, is accomplished and the focallength in the horizontal plane is halved. The upstream dispersion lenses38 and 38' increase the taking angle.

The parallel incident light beams in the I.O.D. spacing pass through thetwo optical systems and pass out of the cylindrical lenses 37 and 37'.The two resulting anamorphotically compressed images correspond to aleft image and a right image, which are what the eyes perceive of anobject. The two interocular-correlated images must then be representedin juxtaposed manner on the film plane without further optical change.

The symmetrical deflection of the L/R-images takes place by means of asystem of prisms 30, 31, 31'. The prisms are silvered on the opticallyactive surfaces. Prism 30 is arranged over the film plane and isstationary. Prisms 31 and 31' are positioned behind the individualanamorphotic systems 35 and 35', and are displaceable in oppositedirections. Arrows L, L' show the path of light beams from theanamorphotic attachments to the film plane. The film plane is subdividedinto two areas 2 and 2' with one of the two L/R-images represented ineach area. The image centres have the reduced spacing TIOD correspondingto a linear-transformed interocular distance.

The silvered prisms, which can be replaced by corresponding mirrors, aredimensioned and arranged such that the desired deflection is obtainedand the overall length is minimized. Two deflections by 90° isparticularly favorable.

In wide-angle photographs possible by this optical arrangement, thereare considerable convergence variations in the close range, whichvariations must be correspondingly compensated. A parallel displacementof the image rays is necessary to restore the variable spacing (TIOD) ofthe associated image points on the film plane. This is accomplished byan oppositely directed displacement of the two prisms 31 and 31'positioned behind the anamorphotic attachments. The oppositely directeddisplacement is indicated by the two oppositely directed arrows P, P'.

During displacement of the two prisms toward one another, the twoparallel, associated rays move apart in the film plane. During movementof the prisms away from one another, the associated image points in theL/R-areas of the film plane move towards one another. The convergencefor any taking distance can be restored in this simple way.

Simultaneously with these oppositely directed displacements of the twoprisms 31, 31' and as a function of the prism positions, the image raysL, L' emanating from lenses 37, 37' follow longer or shorter paths tothe film plane 2 or 2'. With an appropriate choice of basic optics 10,10', this image space-side lengthening or shortening of the light pathsimultaneously provides the necessary focusing of the image on changingthe taking distance. This prism arrangement and the oppositely directeddisplacement of two prisms with respect to a stationary prism permits asingle manipulation to simultaneously correct the divergence and thefocusing. In addition, the two prisms 31, 31' are the only movingoptical parts in this arrangement. Thus, all the setting and adjustingfunctions when taking a photograph are carried out with a minimum ofmovable parts.

Advantageously, the movement of the prisms is brought about by arelatively solid rod with end bearings and with two oppositely directedthreads. A manipulating member for turning the threaded rod is providedon one end of the threaded rod outside the bearings. The calibration ofthe regulating member is carried out in known manner.

The optical arrangement of the present invention permits extremewide-angle photographs to be taken for stereo projection with cameraconstructions of previously unknown compactness. This is also noteworthyfrom the weight standpoint. On the basis of the presently describedsystem, hand-held cameras can be constructed, which are easy tomanipulate and require only the simplest operating manipulations. Thissystem is also suitable for all film sizes, the downward limitation onlybeing the available film surface.

While various embodiments have been chose to illustrate the invention,it will be understood by those skilled in the art that various changesand modifications can be made therein without departing from the scopeof the invention as defined in the appended claims.

I claim:
 1. An optical arrangement for producing two anamorphotic images correlated by an interocular base distance, comprising:first and second basic optical systems spaced laterally by an interocular base distance, each of said basic optical systems having an object space side and an image space side; and first and second afocal anamorphotic systems mounted adjacent said first and second basic optical systems, respectively, each of said anamorphotic systems having a cylindrical negative lens system on the object space side of the respective basic optical system and a cylindrical positive lens system on the image space side of the respective basic optical system.
 2. An optical arrangement according to claim 1 wherein reflecting mirror means are mounted downstream of said positive lens systems for reducing spacing of the two anamorphotic images.
 3. An optical arrangement according to claim 2 wherein said reflecting mirror means comprises first and second reflecting mirrors arranged on principal optical axes of said first and second basic optical systems, respectively, said first and second reflecting mirrors being relatively movable in directions orthogonal to said principal optical axes.
 4. An optical arrangement according to claim 3 wherein said reflecting mirror means comprise third and fourth reflecting mirrors fixed relative to said principal axes and receiving light reflected from said first and second reflecting mirrors.
 5. An optical arrangement according to claim 2 wherein said reflecting mirror means comprise a pair of reflecting mirrors fixed relative to principal optical axes of said first and second basic optical systems and arranged in a reflected light beam.
 6. An optical arrangement according to claim 5 wherein said reflecting mirrors comprise surface-silvered, 90° reflecting prisms.
 7. An optical arrangement according to claim 4 wherein said reflecting mirrors comprise surface-silvered, 90° reflecting prisms.
 8. An optical arrangement according to claim 3 wherein said reflecting mirrors comprise surface-silvered, 90° reflecting prisms.
 9. An optical arrangement according to claim 2 wherein said reflecting mirror means includes reflecting mirrors comprising surface-silvered, 90° reflecting prisms.
 10. An optical arrangement according to claim 9 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 11. An optical arrangement according to claim 8 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 12. An optical arrangement according to claim 7 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 13. An optical arrangement according to claim 6 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 14. An optical arrangement according to claim 5 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 15. An optical arrangement according to claim 4 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 16. An optical arrangement according to claim 3 wherein each of said reflecting mirrors are oriented at an angle of about 45° relative to said principal optical axes.
 17. An optical arrangement according to claim 2 wherein said reflecting mirror means comprises reflecting mirrors oreinted at angles of about 45° relative to optical axes of said first and second basic optical systems. 